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Posted on Tue, Oct 12, 2010 : 3:01 p.m.

Garden Faerie: Dahlias add great fall color to your garden

By Monica Milla

Dahlias are some of my favorite late-season bloomers. The flowers come in many colors, forms, and sizes (from 10 inches to 6 feet tall).

Dahlias bloom from late summer through frost and add a bright burst of color into the fall landscape. Whether you treat them as annuals or dig them up and store them over the winter, I encourage you to give dahlias a try.


Dahlia 'Kerri Fruit Salad' is one of the 100 varieties of dahlias grown at Valentine Gardens in Whitmore Lake. (The gardens are not open to the public, but you can buy the dahlias at the Ann Arbor Farmer's Market.)

Monica Milla | Contributor

A couple of years ago I had the opportunity to visit Valentine Gardens in Whitmore Lake where Tom and Lil Rumple grow 100 varieties of dahlias; with a total of 700 dahlia plants. It was amazing seeing so many varieties of dahlias in one location.

I tend to prefer the kind of crazier-looking dahlias, like the spiky, bright "Hollyhill Spiderwoman."


Dahlia 'Hollyhill Spiderwoman'

Monica Milla | Contributor

I also love anything orange, like this "Stella R." If you look closely, you'll see the colors are actually pink and yellow, but from a distance the petals look orange.


Dahlia 'Stella R'

Monica Milla | Contributor

The ideal soil for dahlias contains 25 percent organic material mixed into sandy loam. If your soil tends to be more clayey, you can amend it with some peat or compost so it drains better. (Do not add sand. Sand + clay = cement. I've noticed my own dahlias haven't minded the clay, so I haven't amended.) The dahlia's shallow root system likes to be kept moist, so Tom uses grass clippings (which are mostly water and decompose quickly) and leaves as mulch.

Dahlias are tender perennials with root tubers. They can overwinter in warmer climates, but not in Michigan. You either need to dig them up and store them over the winter, or view them as annuals. 

Not surprisingly, Tom has developed a system for digging up and storing his 700 plants, and most of his techniques work on the smaller scale as well. Whenever the first frost kills the dahlia leaves, Tom cuts off the stalks to about 6 inches. He then uses a garden potato fork to gently nudge the tubers out of the ground. He pulls the tubers out by the remaining stalk, using it as a handle.


Dahlia 'Clearview Erin'

Monica Milla | Contributor

He then hoses off the clumps, and lets them air dry, out of the sun, for a week. He says the tubers contain 90 percent moisture when they are dug up, and they should only contain about 50 percent moisture for winter storage. After the week of air drying, he trims the finer hair roots off the clump, cuts the ends off any very long tubers, and cuts the stalk down flush with the stump. If the tubers are very big, you can divide them at this point as well.

He then puts two to four clumps of tubers in a plastic grocery bag and covers them with vermiculite. He also labels the tubers! He does not tie the bags, and stores them inside a cardboard box with a lid. He stores the boxes in a special area of his basement where the temperature is below 50 but above freezing. This temperature range is ideal, Tom says, but it's difficult for most people to achieve: basements tend to be too warm and garages tend to be too cold. Refrigerators are too moist and also not a good option.


Dahlia 'Bodacious'

Monica Milla | Contributor

In early summer, say June 1, you can plant out you. Plant a hole about 12 inches deep and add the amended soil mix about 10 inches deep. Set the dahlia tuber with the stalk (or eye) side up on the soil mix and then cover with no more than two inches of soil. Water thoroughly until the plant grows, and then water thoroughly about once a week, or more if it's quite hot. Tom uses rebar stakes and jute twine to stake his plants. 

As the plant grows, he adjusts the twine accordingly. He does not cut back the plant at any time. Another dahlia grower mentioned that when the plant gets four to five sets of leaves, she pinches out the center stalk, which will create more branches and therefore more flowers.

For very tall or large blooms, like the beautiful burgundy "Spartacus" below, Tom uses plastic hair clips to attach the stalk to the stake. (That's where I learned the secret of hair clips as plant ties!)


Dahlia 'Spartacus'

Monica Milla | Contributor

Another thing I learned is that dahlias are freaks! They are true to form from the tuber, but not the seed. This means that creating new varieties is essentially guess work, taking at least four years. Normally growers cross pollinate plants to get new varieties, combining a color characteristic of one plant, say, with a hardiness level of another plant. With dahlias, this does not work, as a plant grown from seed will not look like its parent plant. Not only that, but each seed of one dahlia bloom could produce a different type of new plant!

Also check out this video on how to divide your tubers after digging out and before storing.

Monica Milla, the Garden Faerie, is a master gardener volunteer, garden speaker, garden coach and author of "Fun with Winter Seed Sowing."


Monica Milla

Tue, Oct 12, 2010 : 8:47 p.m.

Cash, I'm not sure of standard roses need dormancy to rebloom. If they don't you could just bring it in your house and treat it like a houseplant, like tropical hibiscus, say. If it does need a period of cold, your garage is probably best. MBT, there are white & yellow dahlias, too, but Japanese beetles prefer them to the other colors (at least in a major growing operation like I visited), so this grower had the yellow & white ones under netting and it wasn't as great a photo op. What is it about yellow, anyway? Yellow roses tend to be the least winter-hardy, too.


Tue, Oct 12, 2010 : 8:27 p.m.

I Want Spartacus! Great pics and tips Monica. Now that you mention it I wonder what happened to my dahlias I bought a few years ago. I'm going to have to replace mine with 'Spartacus.' Even though I hate pink blooms 'Stella R' is lovely and kinda, maybe sorta, took my breath away when I scrolled down and saw it.


Tue, Oct 12, 2010 : 5:16 p.m.

Monica, I understand. Just when you think life gets easier...... I got a rose tree as a gift this year. Now.....goodness I am stressed as to how I should overwinter it. I have read a cool basement or garage where it doesn't freeze, could hold it dormant. Or I could lay it sideways and bury it with dirt and some mulch over it. I guess I'll try the basement.

Monica Milla

Tue, Oct 12, 2010 : 4:04 p.m.

Epengar, I agree it's difficult to tell "hard news" from "personal commentary." If the byline is followed by "community contributor" or just "contributor" is means personal opinion/blogger, not reporter. To further complicate matters, my professional background is writing/editing, so my blog entries do sometimes read more like news articles than personal reflections.


Tue, Oct 12, 2010 : 3:28 p.m.

Monica, thanks for the clarification. I didn't realize that this was a particular series, or that it's just yours. For me at least,'s layout doesn't make that clear. It just looks like a general gardening article to me.

Monica Milla

Tue, Oct 12, 2010 : 3:08 p.m.

A2K & Cash, Last year I let some of my dahlias freeze, and sent some to a friend in Alabama where they can overwinter in the soil. Just when I thought my life was gonna be free and easy, a local friend gave me her dahlias that she'd managed to overwinter but didn't want to plant this spring. I already dug some out and gave them to my mom, who has a microclimate in one corner of her garden where they overwinter, and now I'm now deciding whether I'll bother to bring in the rest or let them freeze... I think dahlias are the plant that keeps on giving! :)


Tue, Oct 12, 2010 : 2:32 p.m.

Monica, Great article and great pictures!!! I gave up dahlias a few years ago, trying to make my senior years a little less work. (every year something gets left out to freeze! LOL) But that doesn't mean I don't drool when looking at pictures and reading about them. Thanks!


Tue, Oct 12, 2010 : 2:16 p.m.

I started growing bedding dahlias about 10 years ago, and the past few years have graduated to cactus and waterlilly types...WARNING, growing Dahlias is completely addictive, I started with 3 plants, now I have 20 :O) I have good luck storing the tubers in gallon-size ziplocks filled with sterile seed-start medium and stashing them in our basement bathroom with the heating ducts closed off.

Monica Milla

Tue, Oct 12, 2010 : 12:53 p.m.

Epengar, I love OHG and have ordered from them before. If you ever get the chance to hear Scott Kunst speak, he is a font of info and very entertaining. This blog is about my personal gardening experience. I happened to be on a tour of Valentine Gardens through a friend in the Ypsi Garden Club; I have no personal connection to them otherwise. I mentioned them solely as the backdrop to where I took the photos, and quoted the owner because he shared a lot of valuable info. Had I attended a dahlia tour at OHG, they would have been mentioned as the backdrop. I don't use my blog to plug businesses or products. I'm frugal and don't buy a lot of things, and I prefer to plug volunteer organizations. welcomes content from the public and I'm sure would be very open if you wanted to start a blog reviewing garden products or services.


Tue, Oct 12, 2010 : 12:31 p.m.

I'm a little disappointed that this article didn't mention Old House Gardens, an Ann Arbor business that sells a world-class collection of rare, antique, and heirloom varieties of flower bulbs. They have a good website, with tons of information: Old House Gardens sells varieties that you can't get anywhere else, beautiful things. We got a set of dahlias from them several years ago that are still going strong. I especially like the Winsome and Little Beeswings varieties. I've done business with them for years, and have always had good service and gotten healthy viable bulbs and tubers. They do most of their business by mail-order, and are known all across the country, but you can pick up merchandise at their business in town if you like. They do gift certificates too, which make a nice house-warming gift. I don't work there, and have no connection except as a very satisfied customer. I'm just posting to put in a plug for a great local business.